Parallel jaw pliers



E. RICHARDSON PARALLEL JAW PLIERS Aug. 31, 1954 Filed Feb. 15. 1949y 2 Sheets-Sheet 1 Il.. l will IN V EN TOR.

Er'msfllll zc'h ardsam B A r rokN s patented ug. 31V, 1954 UNITED STATES PATENT OFFICE 2,687,661 PARALLEL JAW PLIERS Santa Barbara, Calif.

Ewell Richardson,

Application February 15, 1949, SerialNo.

6 Claims. (o1. s1 46) mounted in said jaws and slidably said cam slots.

The arms of the pliers are closed; Fig. 2 is a sectional View on line 2 2 of Fig. 1; Fig. 3 is a deta view of the jaw pin guide plates;

Fig. 4 is a view taken on line 4 4 of Fig. 5 with the jaws in open position with parts in section;

Fig. 5 is a sectional View of Fig. 4 taken on line 5 5 with parts broken away;

Fig. 6 is a section showing the Fig. '1 Fig. 5;

Fig. 8 is a section taken on Fig. 9 is a perspective view 6'; a d

Fig. 10 is a perspective view of the lower handle 1.

taken on line 6 6 of` Fig. 1, cutting portion of the jaws; is a sectional view taken on line 1 1 of line 8 8 of Fig. 1; of the upper handle II) and II and I 4 and I5,A respectively. Cam plates I and I carry bores on the center line c b of the plates to receive the pivot pin 5` and rivet 5. A collar 4 surrounds pin 5. The

end of the llnks pin 5 is positioned in' the bore 5a in the cam plate intermediate the slots If-I and I5 and intermediate the slots I Il and I4, and the Thus the center line bisects the II and between the slots I 4 and I5.

The cam plates I and I' are each provided with slots 25 positioned on the center line of The arms` B and 1 are forked (see 10) over the jaws and plates I and The passes and 1 of the pliers are `formed outer ends with the cutting jaws 6 and 1 from a full open position (Fig. 5) to closed position (Fig. 1) the around the hinge pin.

The line connecting center of pins I3 and I2 Lacct/,cci

and also the line connecting pins 8 and 9 are perpendicular to the center line ab throughut the movement oi the jaws.

It will be observed that theiorce exerted by the arm 6 or 'i' on the jaws 5 and 1, respectively, is exerted upon the pins I2 and I3, respectively. This lever system is a lever of the second class and the mechanical advantage is dependent upon the separation between pins and I3 or 5 and I2. The closer the pins 5 and I3 and also the closer the pins 5 and l2 `are together the greater the mechanical advantage. It will be observed that as the jaws are opened more and more, the length of lever arm between 5 and I3 and rbetween 5 and I2 is shortened by the movement of the pins l2 and I3 in the cam slots i8 and l5 'and in the slots I4 and I5. The links 2i), 20', and 2l and 2|', as stated above, are provided with pin 2li slidably positioned in the slot 25 located at the inner end ci the plates I and I. Thus, when the arms t and I are moved toward or away from each other, the cam plates I and l are maintained in their proper orientation with the parallel jaws 6 and i as they are caused to open or close.

While l have described a particular embodif ment of my invention for the purpose of illustration, it should be understood that various modiiications and adaptations thereof may be made within the spirit of the invention as set forth in the appended claims.

1 claim:

1. Variable spanning pliers, comprising a pair oi jaws, one on each side of avcenter line of said pliers, lever arms, a pivot for said lever arms mounted at one end of said arms, slide pins mounted in said jaws, a Cam plate, and two pairs of parallel cam slots in said plate, each pair oi said cam slots being disposed at an acute angle to the center line oi said pliers, said slide pins being slidably positioned in said cam slots, means on said lever arms for slidably moving said slide pins in said cam slots to actuate said jaws, said pivot being mounted in said cam plate.

2. Variable spanning pliers, comprising a pair of jaws, one on each side 0i the center line of said pliers, lever arms, a pivot for said lever arms mounted at one end of said arms, slide pins mounted in said jaws, a cam plate, two pairs of parallel cam slots in said plate, Said slide pins being slidably positioned in said cam slots, said pivot being mounted in said cam plates, and means on said arms for slidably moving said slide pins in said cam slots to actuate said jaws.

3. A plier comprising a pair of jaws, means for moving said jaws to and 'from each other, said means comprising a pair of spaced slide pins mounted in one of 'said jaws, `a cam plate, spaced parallel cam slots in said cam plate, the spaced slide pins in one of said jaws being positioned one in each of said parallel slots, a lever arm, a pivot pin in said cam plate, said lever arm being hingedly mounted on said pivot pin in said cam plate, cam faces on said arm operatively engaging one of said slide pins, said cam faces being for-med to move said one slide pin in the cam slot in which it is positioned on movement of said arm, and a second lever arm associated with the other of said jaws.

4. A plier comprising a pair oi jaws, a pair of spaced slide pins mounted in one of said jaws, a cam plate, a pair of spaced parallel cam slots in said cam plate, the spaced slide pins in one oi said jaws being positioned one in each of said parallel slots, a lever arm hingedly lmounted on a pivot positioned in said cam plate, cam faces on said arm operatively engaging one of said slide pins, said cam faces being formed to move said one slide pin in the cam slots in which it is positioned on movement of said arm, a second pair of spaced slide pins mounted in the other of said jaws, a second pair of spaced parallel cam slots positioned in said cam plate, the said second mentioned slide pins being positioned one in each of said second mentioned cam slots, a second lever arm hingedly mounted on said pivot, and cam faces in said second arm operatively engaging one of .said second mentioned slide pins, said second mentioned cam faces being formed to move said one second mentioned slide pin in its cam slot on movement of said second lever arm.

5. A plier comprising a pair of jaws, means for moving said jaws to and from each other, said means comprising a pair of spaced slide pins mounted in one oi said jaws, a pair of cam plates, one on each side of said jaws, a `pair oi spaced parallel cam slots in each oi said cam plates, the spaced slide pins in one of said jaws being positioned one in each of said parallel slots in each of said plates, a lever arm hingedly mounted on a pivot mounted in said cam plates, cam aces in said arm operatively engaging one of said slide pins, said cam aces being formed to move said one slide pin in the cam slot in which it is `positioned on movement or said arm, and a `second lever arm associated with the other of said jaws.

`6. A plier comprising a pair o jaws, a pair of spaced slide pins mounted `in one oi' said jaws, a pair of `cam plates, one on each side of said jaws, a pair oi spaced parallel cam slots in each or said cam plates, the spaced slide pins in `one oi said jaws being positioned one in each oi said parallel slots in each of said plates, a lever arm hingedly mounted on a p'vot mounted in said cam plates, cam faces in said arm operatively engaging one of -said slide pins, said cam faces being formed to move said one slide pin in the .cam slot in which it is positioned on movement of said arm, a second pair of spaced slide pins mounted von the other of said jaws, a second pair of spaced parallel cam slots positioned in each A'ci said cam plates, the said second mentioned .slide pins being positioned one in each oi said second mentioned cam slots, a second lever arm hingedly mounted .on said pivot, cam faces in said second arm operatively engaging one of said second kmentioned slide pins, said second mentioned cam faces being formed to move said one second mentioned slide pin in its cam slot, maintaining said jaws in parallel relation, a pair of links, `a link hinge pin for said links, each of said links being hingedly connected, .one to each of said arms, a slot positioned on the center line oi each of said plates, said link hinge pin being slida'bly positioned -in said last-named slot.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain Aug. 25, 1927 

